Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing 100083, China.
School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007, China.
Sci Total Environ. 2018 Mar;616-617:417-426. doi: 10.1016/j.scitotenv.2017.10.314. Epub 2017 Nov 8.
Urban trees have the potential to reduce air pollution, but the retention capacity and efficiency of different tree species for atmospheric particulate matter (PM) accumulation and the underlying mechanism hasn't been well understood. To select tree species with high air purification abilities, the supplementing ultrasonic cleaning (UC) procedure was first introduced into the conventional leaf cleaning methods [single water cleaning (WC) or plus brush cleaning (BC)] for eluting the leaf-retained PM. Further updates to the methodology were applied to investigate the retention capacity, efficiency, and mechanism for PM of five typical greening tree species in Beijing, China. Meanwhile, the particle size distribution of PM on the leaves, the PM retention efficiencies of easily removable (ERP), difficult-to-remove (DRP) and totally removable (TRP) particles on the leaf (AE), and the individual tree scales were estimated. The experimental leaf samples were collected from trees with similar sizes 4 (SDR) and 14days (LDR) after rainfall. When the leaves were cleaned by WC+BC, there was, on average, 29%-46% of the PM remaining on the leaves of different species, which could be removed almost completely if UC was supplemented. From SDR to LDR, the mass of the leaf-retained PM increased greatly, and the particle size distribution changed markedly for all species except for Sophorajaponica. Pinus tabuliformis retains particles with the largest average diameter (34.2μm), followed by Ginkgo biloba (20.5μm), Sabina chinensis (16.4μm), Salix babylonica (16.0μm), and S. japonica (13.1μm). S. japonica and S. chinensis had the highest AE to retain the TRP and ERP of both PM and PM, respectively. Conversely, S. babylonica and P. tabuliformis could retain both TRP and ERP of PM and PM, and PM and TSP with the highest AE, respectively. In conclusion, our results could be useful in selecting greening tree species with high air purification abilities.
城市树木具有减少空气污染的潜力，但不同树种对大气颗粒物（PM）积累的截留能力和效率及其潜在机制尚未得到很好的理解。为了选择具有高空气净化能力的树种，首次在常规叶片清洗方法（单一水洗（WC）或加刷清洗（BC））中引入补充超声清洗（UC）程序来洗脱叶片截留的 PM。进一步更新了方法学，以研究中国北京五种典型绿化树种对 PM 的截留能力、效率和机制。同时，估计了叶片上 PM 的粒径分布、叶片上易去除（ERP）、难去除（DRP）和完全去除（TRP）颗粒物的 PM 保留效率（AE）和单株树尺度。实验叶片样本取自雨后 4 天（SDR）和 14 天（LDR）的相似大小的树木。当叶片用 WC+BC 清洗时，不同物种叶片上的 PM 平均仍有 29%-46%残留，如果补充 UC，则可几乎完全去除。从 SDR 到 LDR，所有物种的叶片截留 PM 质量显著增加，粒径分布明显变化，除了刺槐。油松保留的颗粒物平均直径最大（34.2μm），其次是银杏（20.5μm）、侧柏（16.4μm）、垂柳（16.0μm）和日本樱花（13.1μm）。日本樱花和侧柏的 AE 最高，分别保留 PM 和 PM 的 TRP 和 ERP。相反，垂柳和油松分别能够保留 PM 和 PM 以及 PM 和 TSP 的 TRP 和 ERP 的 AE 最高。总之，我们的结果有助于选择具有高空气净化能力的绿化树种。
